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Mechanically assisted crevice corrosion may disrupt passive oxide films on medical alloys and lead to rapid repassivation reactions which generate corrosion currents and shifts in electrode potential due to the non-equilibrium nature of the reactions and the transient unbalancing of anodic and cathodic reactions. This study presents a theoretical approach to predict currents and voltages over time utilizing the concepts of heredity integrals, area-dependent surface impedance, contact mechanics and the high field physics of oxide repassivation. Two heredity integrals are presented relating, first, the sliding mechanics and oxide film repassivation physics to the current, and second, relating the electrode potential to the current using impedance concepts. Current-potential-time responses to controlled fretting conditions were measured across a fretting frequency from 0.2 to 10 Hz and compared to theoretical results. The coupled integrals were shown to predict the overall current-potential-time behavior for CoCrMo alloy surfaces under several controlled fretting corrosion conditions (loads, sliding speeds, etc.) with a high degree of similarity. These models can be adapted to numerical analyses of tribocorrosion to predict performance., (© 2020 Wiley Periodicals, Inc.)

Poor wear resistance of titanium is a major concern since relative movements due to the cyclic loads in body environment cause wear between the bone and the implant material leading to detachment of the wear debris and release of metal ions due to the simultaneous action of corrosion and wear, defined as tribocorrosion. In order to increase the tribocorrosion resistance, Grade 2 Ti matrix 24vol% B4C particle reinforced composites were processed by hot pressing. Corrosion behaviour was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization in 9g/L NaCl solution at body temperature. Tribocorrosion tests were performed under open circuit potential, as well as under potentiodynamic polarization using a reciprocating ball-on-plate tribometer. Results suggested that the addition of B4C particles provided lower tendency to corrosion and lower corrosion kinetics under sliding, along with significantly reduced wear loss, mainly due to the load carrying effect given by the reinforcement particles., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This study presents an investigation into the tribological, corrosion, and tribocorrosion properties of AISI 316Ti (austenitic) and AISI 430 (ferritic) stainless steels. The comparative analysis focuses on microstructural characterization, hardness, and a series of tribological, electrochemical, and tribocorrosion tests conducted in 0.9% NaCl using a specialized linear tribometer to reveal the quality of the studied materials in tribocorrosion applications. Friction tests were performed under both dry and corrosive conditions, while tribocorrosion tests were conducted under open circuit potential (OCP) conditions in 0.9% NaCl, with the electrode potential of the test specimen monitored during friction. To evaluate the electrochemical behavior of the materials, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were conducted using a 0.9% NaCl solution. The measured corrosion potential (Ecorr) suggests that AISI 430 is thermodynamically more stable than AISI 316Ti; however, AISI 316Ti demonstrated higher polarization resistance (RP) values compared to AISI 430. The findings indicate that material qualities significantly influence the coefficient of friction (CoF). Additionally, a notable antifriction effect of 0.9% NaCl was observed during tribological testing, resulting in a lower CoF compared to dry friction conditions. A cathodic shift in OCP during tribocorrosion testing was also observed in both materials, indicating an increase in corrosion vulnerability when the passive layer is degraded. [ABSTRACT FROM AUTHOR]

In this study, the effect of intermetallic compounds (ICMs) on the tribocorrosion behavior of the 7075 aluminum alloy was investigated. ICMs play important roles in the tribocorrosion resistance and mechanism of the sample. In the as-received sample, micron-sized Mg2Si, Al23Fe4Cu, and nanosized MgZn2 induced pitting corrosion and acted as abrasive materials. Accompanying the re-dissolution of Mg2Si and the growth of MgZn2, the pitting resistance worsened and adhesive wear took place. Subsequently, MgZn2 precipitated along the grain boundaries, which resulted in intergranular corrosion and aggravation of adhesive wear. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study presents an investigation into the tribological, corrosion, and tribocorrosion properties of AISI 316Ti (austenitic) and AISI 430 (ferritic) stainless steels. The comparative analysis focuses on microstructural characterization, hardness, and a series of tribological, electrochemical, and tribocorrosion tests conducted in 0.9% NaCl using a specialized linear tribometer to reveal the quality of the studied materials in tribocorrosion applications. Friction tests were performed under both dry and corrosive conditions, while tribocorrosion tests were conducted under open circuit potential (OCP) conditions in 0.9% NaCl, with the electrode potential of the test specimen monitored during friction. To evaluate the electrochemical behavior of the materials, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were conducted using a 0.9% NaCl solution. The measured corrosion potential (Ecorr) suggests that AISI 430 is thermodynamically more stable than AISI 316Ti; however, AISI 316Ti demonstrated higher polarization resistance (RP) values compared to AISI 430. The findings indicate that material qualities significantly influence the coefficient of friction (CoF). Additionally, a notable antifriction effect of 0.9% NaCl was observed during tribological testing, resulting in a lower CoF compared to dry friction conditions. A cathodic shift in OCP during tribocorrosion testing was also observed in both materials, indicating an increase in corrosion vulnerability when the passive layer is degraded.

This study investigated the corrosion and tribocorrosion behavior of CrN and CrAlN coatings deposited on steel through direct current magnetron sputtering. Additionally, the effects of Al addition on the microstructure, corrosion inhibition, and tribocorrosion behavior of CrN coatings were evaluated. Compared with the CrN coating, the CrAlN coating exhibited a denser columnar crystal structure and a higher hardness of 23.8 GPa. The CrAlN coating reacted with water to form Al2O3 and Cr2O3 films, which enhanced its corrosion resistance. Moreover, the addition of Al enhanced the wear resistance of the CrN coating and reduced the material loss due to corrosion, wear, and their synergistic effects. The CrAlN coating exhibited a low corrosion current density of 1.14 × 10−8 A/cm2, indicating a 92% reduction compared with the CrN coating. Furthermore, under either open circuit potential or anodic accelerated tribocorrosion conditions, the CrAlN coating featured significantly lower total material loss and synergistic material loss than the CrN coating, demonstrating higher corrosion and tribocorrosion protection. [ABSTRACT FROM AUTHOR]

This study explores the impact of additive manufactured porous architecture on the tribological performance of Ti6Al4V. Biomimetic porous architectures were manufactured on dense multi-layer using direct energy deposition with a dense layer followed by a porous layer. Varied scanning intervals during laser processing for the porous layer influenced the microstructure and, consequently, the hardness, the corrosion resistance and the tribological behavior of the dense layer. The results indicate a substantial improvement in tribocorrosion performance, particularly noteworthy in reducing corrosive wear rates, making porous architectures beneficial for both biomimetic structures and enhanced tribocorrosion resistance in body fluids. [ABSTRACT FROM AUTHOR]

الملخص: مع التقدم في علوم طب الأسنان والحاجة المتزايدة لتحسين صحة الأسنان، أصبح من الضروري تطوير مواد زراعة جديدة تمتلك خصائص هندسية وميكانيكية وفيزيائية أفضل. البيئة الفموية هي بيئة أكالة، كما أن الحركة النسبية بين الأسنان تجعل البيئة أكثر عدائية. لذلك، يجب دراسة التآكل المشترك وعلم الاحتكاك المعروف باسم تآكل الغرسات. إن الأشكال المعقدة لزراعة الأسنان ومتطلبات الأداء العالي لهذه الغرسات تجعل التصنيع صعبا من خلال عمليات التصنيع التقليدية. مع ظهور التصنيع الإضافي أو الطباعة ثلاثية الأبعاد، أصبح تطوير الغرسات أمرا سهلا. ومع ذلك، فإن المتطلبات المختلفة مثل خشونة السطح، والقوة الميكانيكية، ومقاومة التآكل تزيد من صعوبة تصنيع الغرسات. تستعرض الورقة الحالية الدراسات المختلفة المتعلقة بالغرسات المطبوعة ثلاثية الأبعاد. كما تحاول الورقة تسليط الضوء على الدور الذي يمكن أن تلعبه الطباعة ثلاثية الأبعاد في مجال زراعة الأسنان. هناك حاجة إلى مزيد من الدراسات التجريبية والعددية لاستنباط الظروف المثلى لغرسات الطباعة ثلاثية الأبعاد لتطوير الغرسات ذات الخصائص الميكانيكية والتآكل والبيولوجية المحسنة. Abstract: With the advancements in dental science and the growing need for improved dental health, it has become imperative to develop new implant materials which possess better geometrical, mechanical, and physical properties. The oral environment is a corrosive environment and the relative motion between the teeth also makes the environment more hostile. Therefore, the combined corrosion and tribology commonly known as tribocorrosion of implants needs to be studied. The complex shapes of the dental implants and the high-performance requirements of these implants make manufacturing difficult by conventional manufacturing processes. With the advent of additive manufacturing or 3D-printing, the development of implants has become easy. However, the various requirements such as surface roughness, mechanical strength, and corrosion resistance further make the manufacturing of implants difficult. The current paper reviews the various studies related to3D-printed implants. Also, the paper tries to highlight the role of 3D-Printing can play in the area of dental implants. Further studies both experimental and numerical are needed to devise optimized conditions for 3D-printing implants to develop implants with improved mechanical, corrosion, and biological properties.

Copyright of Journal of Taibah University Medical Sciences is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, anodic TiO 2 ceramic coating was formed on titanium alloys produced by SLM by using the anodization method. After then, hybrid ceramic coatings are produced by combining a formation of ZrO 2 nanostructures in the TiO 2 coating with the SILAR technique. The microstructure, wettability, electrochemical properties, and tribocorrosion behavior of anodic TiO 2 and hybrid ceramic coatings were also investigated. According to XRD results, two TiO 2 peaks are observed in anodic TiO 2 films. After the SILAR process, the tetragonal-ZrO 2 , and monoclinic-ZrO 2 with TiO 2 peaks were obtained in the hybrid ceramic coatings. Especially, while the intensity of the TiO 2 peaks decreased, the intensity of the ZrO 2 peaks increased with the increase in cycle time. The surface wettability experiments indicate that the HB-80 specimen exhibits superhydrophobic behavior, and it also has the highest contact angle value among all specimens. Corrosion tests in SBF solution confirmed that hybrid ceramic films importantly increased the anticorrosion performance of anodic TiO 2 film, depending on the cycle times owing to filling the pores, and the best outcomes for corrosion resistance were obtained from the HB-80 specimen owing to its superhydrophobic properties. Moreover, the results of tribocorrosion tests revealed that all hybrid ceramic films displayed higher tribocorrosion resistance than anodic TiO 2 ceramic film and uncoated Ti6Al4V substrate, and the best performance was seen from the HB-80 specimen due to its decreased porosity and the direct contact area between pin and surface. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) of orthopedic implants has increased in recent years, providing benefits to surgeons, patients, and implant companies. Both traditional and new titanium alloys are under consideration for AM-manufactured implants. However, concerns remain about their wear and corrosion (tribocorrosion) performance. In this study, the effects of fretting corrosion were investigated on AM Ti-29Nb-21Zr (pre-alloyed and admixed) and AM Ti-6Al-4V with 1% nano yttria-stabilized zirconia (nYSZ). Low cycle (100 cycles, 3 Hz, 100 mN) fretting and fretting corrosion (potentiostatic, 0 V vs. Ag/AgCl) methods were used to compare these AM alloys to traditionally manufactured AM Ti-6Al-4V. Alloy and admixture surfaces were subjected to (1) fretting in the air (i.e., small-scale reciprocal sliding) and (2) fretting corrosion in phosphate-buffered saline (PBS) using a single diamond asperity (17 µm radius). Wear track depth measurements, fretting currents and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analysis of oxide debris revealed that pre-alloyed AM Ti-29Nb-21Zr generally had greater wear depths after 100 cycles (4.67 +/− 0.55 µm dry and 5.78 +/− 0.83 µm in solution) and higher fretting currents (0.58 +/− 0.07 µA). A correlation (R2 = 0.67) was found between wear depth and the average fretting currents with different alloys located in different regions of the relationship. No statistically significant differences were observed in wear depth between in-air and in-PBS tests. However, significantly higher amounts of oxygen (measured by oxygen weight % by EDS analysis of the debris) were embedded within the wear track for tests performed in PBS compared to air for all samples except the ad-mixed Ti-29Nb-21Zr (p = 0.21). For traditional and AM Ti-6Al-4V, the wear track depths (dry fretting: 2.90 +/− 0.32 µm vs. 2.51 +/− 0.51 μm, respectively; fretting corrosion: 2.09 +/− 0.59 μm vs. 1.16 +/− 0.79 μm, respectively) and fretting current measurements (0.37 +/− 0.05 μA vs. 0.34 +/− 0.05 μA, respectively) showed no significant differences. The dominant wear deformation process was plastic deformation followed by cyclic extrusion of plate-like wear debris at the end of the stroke, resulting in ribbon-like extruded material for all alloys. While previous work documented improved corrosion resistance of Ti-29Nb-21Zr in simulated inflammatory solutions over Ti-6Al-4V, this work does not show similar improvements in the relative fretting corrosion resistance of these alloys compared to Ti-6Al-4V. [ABSTRACT FROM AUTHOR]

Today, parts made by additive manufacturing (AM) methods have found many applications in the medical industry, the main reasons for which are the ability to custom design and manufacture complex structures, their short production cycle, their ease of utilization, and on-site fabrication, leading to the fabrication of next-generation intricate patient-specific biomedical implants. These parts should fulfill numerous requirements, such as having acceptable mechanical strength, biocompatibility, satisfactory surface characteristics, and excellent corrosion and wear performance. It was known that AM techniques may lead to some uncertainties influencing part properties and causing significant evaluation conflicts in corrosion outcomes. Meanwhile, the corrosion and wear behavior of additively manufactured materials are not comprehensively discussed. In this regard, the present work is a review of the state-of-the-art knowledge dedicated to reviewing the actual scientific knowledge about the corrosion and wear response of additively manufactured biomedical components, elucidating the relevant mechanism and influential factors to enhance the performance of AM-manufactured implants specifically for the physiological human body fluids. Furthermore, there is a focus on the use of reinforced composites, surface engineering, and a preparation stage that can considerably affect the tribocorrosion behavior of AM-produced parts. The improvement of tribocorrosion performance can have a key role in the production of advanced AM implants and the present study can pave the way toward facile production of high-throughput AM biomedical parts that have very high resistance to corrosion and wear. [ABSTRACT FROM AUTHOR]

This review of the tribocorrosion of coatings and surface modifications covers nearly 195 papers and reviews that have been published in the past 15 years, as compared to only 37 works published up to 2007, which were the subject of a previous review published in 2007. It shows that the research into the subject area is vibrant and growing, to cover emerging deposition, surface modification and testing techniques as well as environmental influences and modelling developments. This growth reflects the need for machines to operate in harsh environments coupled with requirements for increased service life, lower running costs and improved safety factors. Research has also reacted to the need for multifunctional coating surfaces as well as functionally graded systems with regard to depth. The review covers a range of coating types designed for a wide range of potential applications. The emerging technologies are seen to be molten-, solution-, PVD- and PEO-based coatings, with CVD coatings being a less popular solution. There is a growing research interest in duplex surface engineering and coating systems. Surface performance shows a strong playoff between wear, friction and corrosion rates, often with antagonistic relationships and complicated interactions between multiple mechanisms at different scale lengths within tribocorrosion contacts. The tribologically induced stresses are seen to drive damage propagation and accelerate corrosion either within the coating or at the coating coating–substrate interface. This places a focus on coating defect density. The environment (such as pH, DO2, CO2, salinity and temperature) is also shown to have a strong influence on tribocorrosion performance. Coating and surface modification solutions being developed for tribocorrosion applications include a whole range of electrodeposited coatings, hard and tough coatings and high-impedance coatings such as doped diamond-like carbon. Hybrid and multilayered coatings are also being used to control damage penetration into the coating (to increase toughness) and to manage stresses. A particular focus involves the combination of various treatment techniques. The review also shows the importance of the microstructure, the active phases that are dissolved and the critical role of surface films and their composition (oxide or passive) in tribocorrosion performance which, although discovered for bulk materials, is equally applicable to coating performance. New techniques show methods for revealing the response of surfaces to tribocorrosion (i.e., scanning electrochemical microscopy). Modelling tribocorrosion has yet to embrace the full range of coatings and the fact that some coatings/environments result in reduced wear and thus are antagonistic rather than synergistic. The actual synergistic/antagonistic mechanisms are not well understood, making them difficult to model. [ABSTRACT FROM AUTHOR]

When introduced into the body, the implant interacts with biological environment and may suffer corrosion. In addition, when this implant is submitted to friction, it may degrade by tribocorrosion due to the simultaneous action of corrosion by the body liquid and mechanical wear. Both corrosion and tribocorrosion are connected to the presence of proteins that cover the surface implant. The latter plays an ambiguous role on corrosion since dozens of contradictory papers pointed out their beneficial or detrimental effect. After its introduction into the body, the implant should form a direct interface with bone through structural and functional connection. The osseointegration and the strength of interfacial bond depend on surface properties of the implant, namely, its topographical and physico-chemical properties. In addition, since bone cells are sensitive to the species produced during the implant corrosion, when corrosion occurs, this may lead to impact osseointegration and to cause implant loosening. There is a strong connection between corrosion and osseointegration, both of which are worth discussion. That is the object of the present narrative review where we will discuss: (1) corrosion and tribocorrosion of titanium alloys used as biomaterials paying particular attention to the influence of proteins, (2) the effect of implant roughness and surface energy on osseointegration.

Tribocorrosion, a research field that has been evolving for decades, has gained renewed attention in recent years, driven by increased demand for wear- and corrosion-resistant materials from biomedical implants, nuclear power generation, advanced manufacturing, batteries, marine and offshore industries, etc. In the United States, wear and corrosion are estimated to cost nearly USD 300 billion per year. Among various important structural materials, passive metals such as aluminum alloys are most vulnerable to tribocorrosion due to the wear-accelerated corrosion as a result of passive film removal. Thus, designing aluminum alloys with better tribocorrosion performance is of both scientific and practical importance. This article reviews five decades of research on the tribocorrosion of aluminum alloys, from experimental to computational studies. Special focus is placed on two aspects: (1) The effects of alloying and grain size on the fundamental wear, corrosion, and tribocorrosion mechanisms; and (2) Alloy design strategies to improve the tribocorrosion resistance of aluminum alloys. Finally, the paper sheds light on the current challenges faced and outlines a few future research directions in the field of tribocorrosion of aluminum alloys.

Titanium dioxide nanotubes (TNTs) have been extensively researched for their enhanced biomedical characteristics, including biocompatibility, cell apposition, and growth morphology. However, there is a significant concern in metallic medical devices owing to micro-movements between implants and bone in aggressive environments due to wear and corrosion synergies, leading to adverse body responses and implant failure. In this study, TNTs on Commercially Pure titanium (C.P. Ti) with three different thickness layers were grown to correlate their corrosion and wear behavior. Initially amorphous after anodization, TNTs underwent annealing at 450 °C for 2 h to transform the distorted, into a crystalline structure. The characterization included X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX), X-ray Photoelectron Spectroscopy (XPS), and contact profilometry. Potentiodynamic polarization (PD) and tribocorrosion tests were conducted in Simulated Body Fluid Electrolyte (SBF). SEM micrographs showed TNT thickness layers of 314, 691, and 5280 nm, and X-ray Diffraction showed anatase transformation post-annealing. Results confirmed a significant influence of TNT thickness layers on corrosion and tribocorrosion properties, with higher current density obtained from PD for thicker TNTs layers, associated with surface fluorine content. During tribocorrosion, annealed samples demonstrated lower corrosion tendency, potential drop, and coefficient of friction. Morphology of worn surfaces and volumetric wear rate varied with TNT thickness layer and thermal treatment.

Additive manufactured Ti6Al4V has shown high tensile anisotropy. The tribocorrosion properties involve the coupling of mechanical wear and surface corrosion, and its anisotropy is unclear. In this study, the corrosion resistance of the horizontal (XOY) plane and the vertical (V) plane was compared by electrochemical tests. The wear resistance and tribocorrosion resistance of different planes of laser powder bed fusion (L-PBF) Ti6Al4V were tested by using zirconia ball as friction pair. The results show that the corrosion resistance of the V plane was better than that of the XOY plane. However, the wear and tribocorrosion resistance recorded for the XOY plane was better than that of the V plane. The columnar crystals along the building direction led to the anisotropy of wear and tribocorrosion of L-PBF Ti6Al4V.

When introduced into the body, the implant interacts with biological environment and may suffer corrosion. In addition, when this implant is submitted to friction, it may degrade by tribocorrosion due to the simultaneous action of corrosion by the body liquid and mechanical wear. Both corrosion and tribocorrosion are connected to the presence of proteins that cover the surface implant. The latter plays an ambiguous role on corrosion since dozens of contradictory papers pointed out their beneficial or detrimental effect. After its introduction into the body, the implant should form a direct interface with bone through structural and functional connection. The osseointegration and the strength of interfacial bond depend on surface properties of the implant, namely, its topographical and physico-chemical properties. In addition, since bone cells are sensitive to the species produced during the implant corrosion, when corrosion occurs, this may lead to impact osseointegration and to cause implant loosening. There is a strong connection between corrosion and osseointegration, both of which are worth discussion. That is the object of the present narrative review where we will discuss: (1) corrosion and tribocorrosion of titanium alloys used as biomaterials paying particular attention to the influence of proteins, (2) the effect of implant roughness and surface energy on osseointegration. [ABSTRACT FROM AUTHOR]

Tribocorrosion, a research field that has been evolving for decades, has gained renewed attention in recent years, driven by increased demand for wear- and corrosion-resistant materials from biomedical implants, nuclear power generation, advanced manufacturing, batteries, marine and offshore industries, etc. In the United States, wear and corrosion are estimated to cost nearly USD 300 billion per year. Among various important structural materials, passive metals such as aluminum alloys are most vulnerable to tribocorrosion due to the wear-accelerated corrosion as a result of passive film removal. Thus, designing aluminum alloys with better tribocorrosion performance is of both scientific and practical importance. This article reviews five decades of research on the tribocorrosion of aluminum alloys, from experimental to computational studies. Special focus is placed on two aspects: (1) The effects of alloying and grain size on the fundamental wear, corrosion, and tribocorrosion mechanisms; and (2) Alloy design strategies to improve the tribocorrosion resistance of aluminum alloys. Finally, the paper sheds light on the current challenges faced and outlines a few future research directions in the field of tribocorrosion of aluminum alloys. [ABSTRACT FROM AUTHOR]

To reveal the influence of passive film on the tribocorrosion behaviour of stainless steel, SUS430 was loaded at 2.0 N or 10.0 N in aqueous solutions with various pH from 1.0 to 10.0. The pure wear behaviour was investigated in the air for comparison. The polarization behaviour, the morphology of the worn or tribocorroded surface, and the depth profiles of the formed groove were measured to discuss the mechanism. The passive state was confirmed at pH = 7.0 and 10.0, but vanished at pH = 1.0 and 2.0. The pure wear in air depended on the applied loads, rather than the sliding time. On the other hand, the tribocorrosion in deionised water was much smaller than the pure wear in air. Under a load of 2.0 N, the tribocorrosion at pH = 1.0 was weaker than pH = 2.0. However, the situation reversed when increasing the load to 10.0 N. The tribocorrosion in neutral and alkaline solutions is considerably smaller than in acid solutions. [ABSTRACT FROM AUTHOR]

The challenge of concurrently resisting corrosion, wear, and microbial adhesion in marine equipment necessitates the development of advanced protective coatings for moving parts. Leveraging the unique properties of constituent phases in nanocomposite materials offers a promising approach. Here, we report the development of a high-performance protective coating material combining hard, anti-corrosive, and antifouling TaB 2 phase with a self-lubricating amorphous carbon (a-C) phase. The synthesized specimens form an "a-C embedded in TaCB solid solution" (a-C/TaCB) structure at 8 at.% carbon content and transition to a "TaCB solid solution embedded in a-C" (TaCB/a-C) structure at 18.8 at.% carbon content. The a-C/TaCB coating demonstrates enhanced tribological, corrosion and tribocorrosion performances compared to the TaB 2 coating, while maintaining excellent mechanical and antifouling performances without the usual deterioration caused by an excess soft biocompatible a-C phase. The rational design of this dual-phase nanocomposite structure could facilitate the development of a unique class of protective coating materials tailored to meet the stringent requirements of harsh marine environments. [ABSTRACT FROM AUTHOR]

Nitriding has long been used to engineer the surfaces of engineering steels to improve their surface and subsurface properties. The role of the surface compound layer (γ′-Fe4N and/or ε-Fe2-3N) in improving the tribological and corrosion-resistant properties of nitrided steels has been established. However, there have been very few studies on the response of the compound layer to tribocorrosion in corrosive environments. In this work, the tribocorrosion behavior of a 5 μm thick γ′-Fe4N nitride layer produced on mild steel (MS) by plasma nitriding has been studied in a NaCl-containing solution under various electrochemical conditions. The results show that at a cathodic potential of −700 mV (saturated calomel electrode, SCE), where mechanical wear is predominant, the total material removal (TMR) from the γ′-Fe4N layer is 37% smaller than that from the untreated MS, and at open circuit potential, TMR from the layer is 34% smaller than that from the untreated MS, while at an anodic potential of −200 (SCE), the γ′-Fe4N layer can reduce TMR from mild steel by 87%. The beneficial effect of the γ′-Fe4N nitride layer in improving the tribocorrosion behavior of mild steel is derived from its high hardness and good corrosion resistance in the test solution and its ability to resist both mechanical wear and corrosion and to reduce wear–corrosion synergism. [ABSTRACT FROM AUTHOR]

In this paper, a multi-functional composite coating with low friction coefficient, high wear resistance and excellent tribocorrosion resistance is fabricated on AZ31 Mg alloys by micro-arc oxidation and spray-coating methods. The microstructure, and composition of the coating are characterized by SEM, EDS, XRD, and FT-IR. Potentiodynamic polarization and EIS tests are conducted to evaluate the corrosion resistance of the composite coating. The tribocorrosion property is also studied using pin-on-disk tribometer in 3.5 wt.% NaCl solution. It is found that the composite coating possesses better long-term corrosion resistance than the single MAO coating. The tribocorrosion tests prove that the composite coating exhibits much better wear and tribocorrosion resistance than the single MAO coating and can protect the substrate from corrosion under a sliding condition.

Titanium is the most commonly used material for the production of implants,but titanium dental implants are not immune to corrosion due to the complex oral cavity environments.The concentration of titanium ions increases in tissues around the implants due to the corrosion,leading to allergic reactions and inflammation,which hinder the long-term safe service of implants.In this paper,the research progress on corrosion of titanium implants was reviewed based on different types of influencing factors,including corrosion due to the effect of inorganics and organics,corrosion due to microorganisms and tribocorrosion.Besides,the future research was prospected.

The wear behavior of an as-received Mg-Zn-Y-Zr alloy before and after a facile heat treatment was investigated under sliding in air and 0.5 wt.% NaCl solution. Results revealed that the wear resistance of the alloy was remarkably enhanced after the heat treatment, irrespective of testing condition. The wear mechanism was predominantly abrasive wear accompanied by oxidation under the dry sliding condition, while corrosive wear was dominant under sliding in the NaCl solution. The superior corrosive wear resistance was attributed to the homogenous distribution of fine I-phase precipitates in the alloy by the heat treatment, leading to a reduction in wear, corrosion as well as wear-corrosion synergy. The wear-accelerated corrosion rate was remarkably alleviated after the heat treatment. [ABSTRACT FROM AUTHOR]

Tribocorrosion is a severe problem in dental implants, artificial joints, and other implants, and it will affect the long-term safety of the implants. To improve the deficiencies of titanium alloys, we combined physical vapor deposition technology and anodic oxidation to prepare TiN to embed TiO 2 nanotube composite coatings (NTNTs-TiN). Results show that the hardness of the NTNTs-TiN composite coatings reaches 33.2 ± 0.6 GPa, and the grains of the composite coatings were further refined. The NTNTs-TiN coating has the smallest average coefficient of friction (0.22) during tribocorrosion. The tribocorrosion resistance of NTNTs-TiN coating in SBF is increased by ∼44 and ∼2 times compared with Ti6Al4V alloy and TiN coating, respectively. The capillarity effect of the lower contact angle of NTNTs-TiN can form a continuous water-lubrication film at the interface between the counter-ball and coating and produce a lubrication film composed of Ca, Mg, and P, which reduces the coefficient of friction significantly. The NTNTs/TiN composite coating exhibits the best synergistic effect of wear and corrosion. In addition, the NTNTs-TiN coating also exhibits excellent antimicrobial and corrosion properties, which provides a new solution for the long-term safe use of implants in the human body. [ABSTRACT FROM AUTHOR]

The aim of this in-vitro study was to evaluate the influence of Ag + -ion-coated conditions on the corrosion, tribocorrosion and antibacterial properties of Ti15Mo alloy. The mean wear volume losses of all test specimens after tribocorrosion test procedures were determined using a noncontact 3D profilometer. The specimens' hardness, roughness values and microstructures were measured using the microhardness tester, surface profilometer, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The mean wear volume loss of 30-min Ag + -ion-coated Ti15Mo alloy was lower than the other specimens. In this study, correlations between the hardness, surface roughness and wear volume loss were found to be significant. The PVD coating process enhanced the antibacterial activity of Ti15Mo alloy owing mainly to the formation of silver film on the substrates. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) of orthopedic implants has increased in recent years, providing benefits to surgeons, patients, and implant companies. Both traditional and new titanium alloys are under consideration for AM-manufactured implants. However, concerns remain about their wear and corrosion (tribocorrosion) performance. In this study, the effects of fretting corrosion were investigated on AM Ti-29Nb-21Zr (pre-alloyed and admixed) and AM Ti-6Al-4V with 1% nano yttria-stabilized zirconia (nYSZ). Low cycle (100 cycles, 3 Hz, 100 mN) fretting and fretting corrosion (potentiostatic, 0 V vs. Ag/AgCl) methods were used to compare these AM alloys to traditionally manufactured AM Ti-6Al-4V. Alloy and admixture surfaces were subjected to (1) fretting in the air (i.e., small-scale reciprocal sliding) and (2) fretting corrosion in phosphate-buffered saline (PBS) using a single diamond asperity (17 µm radius). Wear track depth measurements, fretting currents and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analysis of oxide debris revealed that pre-alloyed AM Ti-29Nb-21Zr generally had greater wear depths after 100 cycles (4.67 +/− 0.55 µm dry and 5.78 +/− 0.83 µm in solution) and higher fretting currents (0.58 +/− 0.07 µA). A correlation (R2 = 0.67) was found between wear depth and the average fretting currents with different alloys located in different regions of the relationship. No statistically significant differences were observed in wear depth between in-air and in-PBS tests. However, significantly higher amounts of oxygen (measured by oxygen weight % by EDS analysis of the debris) were embedded within the wear track for tests performed in PBS compared to air for all samples except the ad-mixed Ti-29Nb-21Zr (p = 0.21). For traditional and AM Ti-6Al-4V, the wear track depths (dry fretting: 2.90 +/− 0.32 µm vs. 2.51 +/− 0.51 μm, respectively; fretting corrosion: 2.09 +/− 0.59 μm vs. 1.16 +/− 0.79 μm, respectively) and fretting current measurements (0.37 +/− 0.05 μA vs. 0.34 +/− 0.05 μA, respectively) showed no significant differences. The dominant wear deformation process was plastic deformation followed by cyclic extrusion of plate-like wear debris at the end of the stroke, resulting in ribbon-like extruded material for all alloys. While previous work documented improved corrosion resistance of Ti-29Nb-21Zr in simulated inflammatory solutions over Ti-6Al-4V, this work does not show similar improvements in the relative fretting corrosion resistance of these alloys compared to Ti-6Al-4V.

Today, parts made by additive manufacturing (AM) methods have found many applications in the medical industry, the main reasons for which are the ability to custom design and manufacture complex structures, their short production cycle, their ease of utilization, and on-site fabrication, leading to the fabrication of next-generation intricate patient-specific biomedical implants. These parts should fulfill numerous requirements, such as having acceptable mechanical strength, biocompatibility, satisfactory surface characteristics, and excellent corrosion and wear performance. It was known that AM techniques may lead to some uncertainties influencing part properties and causing significant evaluation conflicts in corrosion outcomes. Meanwhile, the corrosion and wear behavior of additively manufactured materials are not comprehensively discussed. In this regard, the present work is a review of the state-of-the-art knowledge dedicated to reviewing the actual scientific knowledge about the corrosion and wear response of additively manufactured biomedical components, elucidating the relevant mechanism and influential factors to enhance the performance of AM-manufactured implants specifically for the physiological human body fluids. Furthermore, there is a focus on the use of reinforced composites, surface engineering, and a preparation stage that can considerably affect the tribocorrosion behavior of AM-produced parts. The improvement of tribocorrosion performance can have a key role in the production of advanced AM implants and the present study can pave the way toward facile production of high-throughput AM biomedical parts that have very high resistance to corrosion and wear.

FeCrNiMoCBSi amorphous coating was prepared on marine steel F22 using plasma spraying technique for marine protection. The tribocorrosion behavior of Fe-based amorphous coating was explored in simulated seawater. The material loss of the coating in tribocorrosion behavior was attributed to the combination of wear and corrosion. To identify the interaction between wear and corrosion, the friction behavior of the coating was studied at different applied potentials using an electrochemical workstation. These results revealed that wear was a major factor in the material loss of the coating under the present tribology condition, whereas corrosion was retarded due to the good anti-corrosion properties of the Fe-based amorphous coating. The interaction between corrosion and wear in seawater was positive, indicating that corrosion promoted wear and corrosion promoted wear. The findings provide new insights into the wear-corrosion synergy effect on Fe-based amorphous coating under load-chemistry coupled conditions, and offer available supports for the design of marine protective coatings. [ABSTRACT FROM AUTHOR]

The use of additively manufactured components specifically utilizing titanium alloys has seen rapid growth particularly in aerospace applications; however, the propensity for retained porosity, high(er) roughness finish, and detrimental tensile surface residual stresses are still a limiting factor curbing its expansion to other sectors such as maritime. The main aim of this investigation is to determine the effect of a duplex treatment, consisting of shot peening (SP) and a coating deposited by physical vapor deposition (PVD), to mitigate these issues and improve the surface characteristics of this material. In this study, the additive manufactured Ti-6Al-4V material was observed to have a tensile and yield strength comparable to its wrought counterpart. It also exhibited good impact performance undergoing mixed mode fracture. It was also observed that the SP and duplex treatments resulted in a 13% and 210% increase in hardness, respectively. Whilst the untreated and SP treated samples exhibited a similar tribocorrosion behavior, the duplex-treated sample exhibited the greatest resistance to corrosion-wear observed by the lack of damage on the surface and the diminished material loss rates. On the other hand, the surface treatments did not improve the corrosion performance of the Ti-6Al-4V substrate. [ABSTRACT FROM AUTHOR]

It is crucial for clinical needs to develop novel titanium alloys feasible for long-term use as orthopedic and dental prostheses to prevent adverse implications and further expensive procedures. The primary purpose of this research was to investigate the corrosion and tribocorrosion behavior in the phosphate buffered saline (PBS) of two recently developed titanium alloys, Ti–15Zr and Ti–15Zr–5Mo (wt.%) and compare them with the commercially pure titanium grade 4 (CP–Ti G4). Density, XRF, XRD, OM, SEM, and Vickers microhardness analyses were conducted to give details about the phase composition and the mechanical properties. Additionally, electrochemical impedance spectroscopy was used to supplement the corrosion studies, while confocal microscopy and SEM imaging of the wear track were used to evaluate the tribocorrosion mechanisms. As a result, the Ti–15Zr (α + α′ phase) and Ti–15Zr–5Mo (α″ + β phase) samples exhibited advantageous properties compared to CP–Ti G4 in the electrochemical and tribocorrosion tests. Moreover, a better recovery capacity of the passive oxide layer was observed in the studied alloys. These results open new horizons for biomedical applications of Ti–Zr–Mo alloys, such as dental and orthopedical prostheses. [ABSTRACT FROM AUTHOR]

Titanium (Ti) and its alloys are widely used in biomedical applications due to their excellent mechanical properties and biocompatibility. However, they are a concern due to the possibility of cytotoxic effects coming from the degradation products. This degradation occurs by the combined action of corrosion and mechanical wear of these materials, which are released in the biological environment by the biomaterial implanted. The present article aims to investigate a new route to improve electrochemical and tribological performance with surface modification. Regarding the deposition of a protective layer on the surface, it consists of titanium oxide (TiO2) and calcium phosphate (CaP). Both coatings were performed by chronoamperometric methods with titanium oxidation at 1 V and calcium phosphate reduction at −1.5 V. The corrosion and tribocorrosion tests demonstrated the effective combination of TiO2 and CaP layer to protect the Ti substrate. Furthermore, this coating combination reduced corrosion degradation and mechanical wear in PBS, simulating a physiological environment. Additionally, it was observed that this combination of coating decreased the dissipated energy, and consequently, the wear decreased during sliding tests. All these findings indicate the protective behavior of the TiO2 and CaP layer during the tribocorrosion tests. [ABSTRACT FROM AUTHOR]

The simultaneous existence of mechanical erosion and electrochemical corrosion is a common scenario for engineering alloys used in marine environments, such as pump impellers and valves. Nickel–aluminium–bronzes (NABs) are widely used alloys in these environments due to their combination of high corrosion resistance and effective mechanical properties. However, NAB alloys are increasingly cast with reduced nickel content due to its high price and low availability. In this study, we examined the tribocorrosion behaviour of two nickel–aluminium bronzes (C95500 and C95400) with different nickel contents (4.8% and 1.0%, respectively) by means of a pin-on-disk device combined with in situ electrochemistry under 1 M NaCl solution. We conducted tests for pure wear in distilled water, pure corrosion using in situ electrochemistry under 1 M NaCl solution, and a combination of wear and corrosion, called tribocorrosion, to understand the overall synergism that exists between the two. We analysed our results using gravimetric as well as volumetric analysis; in addition, we defined the friction coefficient to compare the effect of open-circuit potential (OCP). We also applied the Tafel method and compared corrosion rates for the different scenarios. We employed confocal microscopy to delimitate the impact of the surface topography of pure wear and its synergistic effect with corrosion, and used an optical microscope to study the materials' microstructures as cast conditions. We also utilised XRD in the Bragg–Brentano configuration to determine the chemical composition of corrosion products. From the experiments conducted, we concluded that an important synergistic effect existed between the wear and corrosion of both NABs, which was associated with corrosion-induced wear. We found NAB C95400 to be more susceptible to erosion under both conditions compared with NAB C95500 due to the chemical composition and lubricant effect of corrosion products formed during the tribocorrosion tests, which were supported by the enriched Ni corrosion products, particularly the presence of nickel-rich copper chloride, 3Cu3(CuNi)(OH)6CuCl2, in the C95500 alloy. We concluded that, because it increased the nickel content, the NAB alloy offered better wear and corrosion behaviour in sea water conditions due to its protective film nature. [ABSTRACT FROM AUTHOR]

The 7075 aluminum alloy in T651 presents interesting properties in high stressed applications, however, it has low surface properties of hardness and chemical stability. Plasma nitriding is an alternative method of raising surface hardness, fatigue resistance, wear and corrosion of alloys. In this work the corrosion and tribocorrosion behavior of AA7075 - T651 with plasma nitriding treatment were studied in comparison untreated alloy. Corrosion behavior was investigated in 3.5 wt.% NaCl solution at room temperature performing potentiodynamic polarization test and electrochemical impedance spectroscopy. Tribocorrosion behavior was investigated using a ball-on-plate tribometer, against an alumina ball, under 1 N normal load and 1 Hz frequency in 3.5 wt.% NaCl solution at room temperature. The corrosion results showed that both conditions exhibited pitting corrosion that occured at corrosion potential. The plasma nitrided alloy presented a concentrated and consequently accelerated corrosion process in the fault regions of the layer formed and the formation of a layer of corrosion products that can act as extra protection. The tribocorrosion results for plasma nitrided alloy indicated a slightly more stable behavior, showing no significant changes in the electrochemical potential during the tribocorrosion test, together with a slightly lower volume and rate of wear. [ABSTRACT FROM AUTHOR]

Morse taper junction tribocorrosion is recognized as an important failure mode in total hip arthroplasty. Although taper junctions are used in almost all shoulder arthroplasty systems currently available in the United States, with large variation in design, limited literature has described comparable analyses of taper damage in these implants. In this study, taper junction damage in retrieved reverse total shoulder arthroplasty (RTSA) implants was assessed and analyzed. Fifty-seven retrieved RTSAs with paired baseplate and glenosphere components with Morse taper junctions were identified via database query; 19 of these also included paired humeral stems and trays or spacers with taper junctions. Components were graded for standard damage modes and for fretting and corrosion with a modified Goldberg-Cusick classification system. Medical records and preoperative radiographs were reviewed. Comparative analyses were performed assessing the impact of various implant, radiographic, and patient factors on taper damage. Standard damage modes were commonly found at the evaluated trunnion junctions, with scratching and edge deformation damage on 76% and 46% of all components, respectively. Fretting and corrosion damage was also common, observed on 86% and 72% of baseplates, respectively, and 23% and 40% of glenospheres, respectively. Baseplates showed greater moderate to severe (grade ≥ 3) fretting (43%) and corrosion (27%) damage than matched glenospheres (fretting, 9%; corrosion, 13%). Humeral stems showed moderate to severe fretting and corrosion on 28% and 30% of implants, respectively; matched humeral trays or spacers showed both less fretting (14%) and less corrosion (17%). On subgroup analysis, large-tapered implants had significantly lower summed fretting and corrosion grades than small-tapered implants (P <.001 for both) on glenospheres; paired baseplate corrosion grades were also significantly lower (P =.031) on large-tapered implants. Factorial analysis showed that bolt reinforcement of the taper junction was also associated with less fretting and corrosion damage on both baseplates and glenospheres. Summed fretting and corrosion grades on glenospheres with trunnions (male) were significantly greater than on glenospheres with bores (female) (P <.001 for both). Damage to the taper junction is commonly found in retrieved RTSAs and can occur after only months of being implanted. In this study, tribocorrosion predominantly occurred on the taper surface of the baseplate (vs. glenosphere) and on the humeral stem (vs. tray or spacer), which may relate to the flexural rigidity difference between the titanium and cobalt-chrome components. Bolt reinforcement and the use of large-diameter trunnions led to less tribocorrosion of the taper junction. The findings of this study provide evidence for the improved design of RTSA prostheses to decrease tribocorrosion. [ABSTRACT FROM AUTHOR]

In this study, DLC coatings with varying thicknesses of CrC interlayers were fabricated on the surface of TC4 alloy by regulating the flow rate of C 2 H 2. The effects of the interlayer layer on the microstructure, mechanical properties, corrosion resistance, and tribocorrosion resistance of DLC coatings were systematically investigated. The results show that as the C 2 H 2 flow rate increases, the CrC interlayer exhibits the structure transitions from columnar crystals to amorphous, resulting in improved hardness. The hardness of the CrC40 interlayer reaches 17.2 GPa, significantly higher than the 9.3 GPa of the Cr underlayer. The CrC interlayer notably enhances the mechanical properties and adhesion strength of DLC coatings. The corrosion current density of the CrC40/DLC coating is 3.07 × 10−8 A/cm2, significantly lower than that of the DLC coating with only a Cr underlayer. Under high load conditions of 20 N, the tribocorrosion rate of the CrC40/DLC coating is reduced to 2.09 × 10−7 mm3.(N.m)−1, representing a significant decrease of 93.9 % compared to the DLC coating. The CrC40/DLC coating exhibits strong adhesion strength, appropriate internal stress and a relatively hard CrC40 interlayer, showing exceptional tribocorrosion resistance. [Display omitted] • The CrC interlayer notably enhances the mechanical properties and adhesion strength of DLC coatings. • The CrC40 interlayer can substantially enhance wear resistance of DLC coatings. • The tribocorrosion resistance of DLC coatings under high load conditions primarily rely on the characteristics of the CrC40 interlayer. [ABSTRACT FROM AUTHOR]

In this paper, a multi-functional composite coating with low friction coefficient, high wear resistance and excellent tribocorrosion resistance is fabricated on AZ31 Mg alloys by micro-arc oxidation and spray-coating methods. The microstructure, and composition of the coating are characterized by SEM, EDS, XRD, and FT-IR. Potentiodynamic polarization and EIS tests are conducted to evaluate the corrosion resistance of the composite coating. The tribocorrosion property is also studied using pin-on-disk tribometer in 3.5 wt.% NaCl solution. It is found that the composite coating possesses better long-term corrosion resistance than the single MAO coating. The tribocorrosion tests prove that the composite coating exhibits much better wear and tribocorrosion resistance than the single MAO coating and can protect the substrate from corrosion under a sliding condition. [ABSTRACT FROM AUTHOR]

We study the influence of hydrogen-sulfide concentration (0–1500 mg/dm3) in chloride-acetate solutions on the corrosion processes, hydrogenation, and corrosion-mechanical wear of 07Kh16N6 steel. It is shown that, independently of its content, the corrosion resistance of steel in these solutions is much lower than in the medium without hydrogen sulfide in which it is passivated. On the steel surface, we observe the appearance of corrosion products in the form of oxide-sulfide compounds whose thickness increases with the hydrogen-sulfide concentration. Their upper layer loses its continuity at a concentration of 1500 mg/dm3. The tribocorrosion characteristics of steel for hydrogen-sulfide concentrations of 100 and 500 mg/dm3 do not undergo substantial changes. At the same time, for 1000 and 1500 mg/dm3 , they decrease by ∼ 30%. The corrosion processes determine the corrosion-mechanical wear of steel in media with different contents of hydrogen sulfide, which is connected with hydrogenation of the surface layers and intense restoration of homogeneous oxide-sulfide films on the surface of friction paths in the case of friction contact. [ABSTRACT FROM AUTHOR]

Metal alloys are one of the most popular materials used in current dental practice. In the oral cavity, metal structures are exposed to various mechanical and chemical factors. Consequently, metal ions are released into the oral fluid, which may negatively affect the surrounding tissues and even internal organs. Adverse effects associated with metallic oral appliances may have various local and systemic manifestations, such as mouth burning, potentially malignant oral lesions, and local or systemic hypersensitivity. However, clear diagnostic criteria and treatment guidelines for adverse effects associated with dental alloys have not been developed yet. The present comprehensive literature review aims (1) to summarize the current information related to possible side effects of metallic oral appliances; (2) to analyze the risk factors aggravating the negative effects of dental alloys; and (3) to develop recommendations for diagnosis, management, and prevention of pathological conditions associated with metallic oral appliances. [ABSTRACT FROM AUTHOR]

A hardening of high velocity oxy-fuel sprayed Inconel 625 coating systems was performed by pulsed plasma nitriding treatment. After deposition of an Inconel 625 coating, samples were pulsed plasma nitrided at 520 °C for 12 h in a gas ratio of 3:1 N2 and H2 under a constant pressure of 2.5 × 102 Pa. Pulsed plasma nitriding improved the microhardness of the high velocity oxy-fuel sprayed Inconel 625 coating from 355 to 401 HV0.05. The high velocity oxy-fuel-sprayed Inconel 625 coating after pulsed plasma nitriding process showed excellent corrosion resistance as well as a reduction of both the friction coefficient and wear rate during the sliding phase in a 3.5 wt.% NaCl solution against sliding action of Al2O3 ball. [ABSTRACT FROM AUTHOR]

Plasma nitriding treatment of 17‐4 precipitation hardening stainless steels was carried out at 400 °C and 450 °C using a direct current unit. The nitriding layer thicknesses of the plasma nitrided at 400 °C and 450 °C were measured as 37.29 μm and 49.97 μm, respectively. The plasma nitrided sample at 400 °C presented dominant martensite and retained austenite phases; however, the height of main martensite diffraction peaks increased at 450 °C. The hardness results demonstrated that the samples at 400 °C and 450 °C were 2.9 and 3.1 times as hard as the untreated sample, respectively. The wear rate values of the sample at 450 °C showed a decrease by 19 % in the corrosive salt solution and 57 % in the dry‐sliding condition compared with that of untreated sample. The corrosion potential of the sample at 400 °C had more positive potential value and lower current density value than those of at 450 °C. The corrosion resistance of the sample at 400 °C improved due to the positive effect of the retained austenite phase. In this study, the wear was more dominant rather than corrosion, therefore plasma nitrided sample at 450 °C showed the best dry wear and tribocorrosion resistance. [ABSTRACT FROM AUTHOR]

Sliding tribocorrosion behaviours of AISI 316 stainless steel were investigated against alumina ball in natural seawater environment (SWE) under 5 N loads. OCP (open circuit potential), potentiostatic (−1 V and 0.3 V) and potentiodynamic measurements were enforced to understand the influence of the sliding wear and electrochemical potential on tribocorrosion behaviours of AISI 316 stainless steel in SWE. Tribocorrosion experiments were conducted with a ball-on-disk type reciprocating tribometer integrated with the three-electrode potentiostat. The wear track surfaces were examined by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and optical profilometry. Mechanical effects reduced corrosion potential under both OCP and potentiodynamic scans in tribocorrosion conditions. Ploughing effects on the wear track were evident at the OCP and −1 V potential because of the predominance of mechanical effects. Pits were determined to develop due to the formation of the galvanic couple between worn and unworn surfaces after the tribocorrosion test, which was conducted under 0.3 V potential. The reduction of the contact area because of the pits and the lubricating effect of the oxides on the surface caused the lowest coefficient of friction (COF) in the wear zone at 0.3 V potential. Besides, COF obtained under −1 V cathodic protection potential (0.35) was less than in OCP condition (0.37) since it only occurred by the wear effects. The study also revealed that material loss from the wear track increased from cathodic potential towards anodic potential.

Nitriding has long been used to engineer the surfaces of engineering steels to improve their surface and subsurface properties. The role of the surface compound layer (γ′-Fe4N and/or ε-Fe2-3N) in improving the tribological and corrosion-resistant properties of nitrided steels has been established. However, there have been very few studies on the response of the compound layer to tribocorrosion in corrosive environments. In this work, the tribocorrosion behavior of a 5 μm thick γ′-Fe4N nitride layer produced on mild steel (MS) by plasma nitriding has been studied in a NaCl-containing solution under various electrochemical conditions. The results show that at a cathodic potential of −700 mV (saturated calomel electrode, SCE), where mechanical wear is predominant, the total material removal (TMR) from the γ′-Fe4N layer is 37% smaller than that from the untreated MS, and at open circuit potential, TMR from the layer is 34% smaller than that from the untreated MS, while at an anodic potential of −200 (SCE), the γ′-Fe4N layer can reduce TMR from mild steel by 87%. The beneficial effect of the γ′-Fe4N nitride layer in improving the tribocorrosion behavior of mild steel is derived from its high hardness and good corrosion resistance in the test solution and its ability to resist both mechanical wear and corrosion and to reduce wear–corrosion synergism.